Mercury switch



May 2, 1939. A. clANcl-n 2,156,971

MERCURY SWITCH Filed May 24, 193e s sheets-sheet 1 Fig. 1. 2 Fig 2 Ill A. CIANCHI MERCURY SWITCH May 2, 1939.

Filed May 24, 1958 3 Sheets-Sheet 2- A fr0/mf f5 May 2, 1939. A. clANcHl 2,156,971

MERCURY SWITCH Filed May 24, 193B 3 Sheets-Sheet 3 Fig. 7. l Fig. 8-

ATTORNEYS,

Patented May 2, 1939 PATENT OFFICE MERCURY SWITCH Alfredo Cianchi, London, England Application May 24, 1938, Serial No. 209,843 In Great Britain April 2, 1937 13 Claims. (Cl. 200-87) 'I'his invention relates to electric switches of the kind comprising a sealed vessel of glass or other fusible insulating material through the wall of which' pass electrodes which are sealed in it as a result of fusion of the material of the vessel and the vessel also enclosing parts including an armature which can be acted upon magnetically to cause electrical connection between the electrodes to be made or broken. The armature may be a plunger or part of a plunger oating in a quantity of mercury or other conducting liquid and the extent of immersion of which in the liquid is changed to cause connection to be made or broken when it is 'acted upon magnetically; in such a case the plunger is usually drawn down into the liquid magnetically to make contact and is released so that it can rise due to its buoyancy to break contact again. The armature may be moved magnetically by a solenoid surrounding the vessel, or by a movable magnet acting on it from outside the vessel.

According to the present invention I make at least one of the electrodes of magnetic material y tion of the magnetised electrode. Two electrodes may be magnetised and the armature brought into the range of one when it moves to an on 'position and 'into the range of the other when it moves to an off position. The electrode may be employed either toY retain the armature in the "on or off position, in which case means is provided to release it again; or, in the case of a switch operated by a solenoid energised by alternating current, to restrain rapid movement of the armature under the action of the alternating current when the armature is being held by the solenoid in the position into which the solenoid moves it. The invention includes other features which will be hereinafter referred to and claimed.

The nine iigures of the accompanying diagrammatic drawings illustrate by way of example nine different ways of carrying the invention into eiect with one particular form of switch. In each of the figures the switch is illustrated in vertical section, and more specifically,

Figure 1 shows a switch designed for operation with alternating current;

Figure 2v is a vertical sectional view of a switch operated with direct current;

Figure 3 is a vertical sectional view of a switch similar to that shown in Figure 2 with a different arrangement for magnetising the holdingv electrode;

Figure 4 is a vertical sectional view of a differient embodiment of a switch incorporating a demagnetising winding With a holding electrode;

Figure 5 is a vertical sectional view of a switch including a sequentially operating switching arrangement for energising the operating windings of the switch;

Figure 6 is a vertical sectional view of a switch similar to that shown in Figure 5 with the incorporation of alternating current with rectiers for selectively energising the operating windings;

Figure 'l is a vertical sectional view of a switch embodying a time delay feature;

Figure 8 is a sectional view of a different embodiment of a switch from that shown in Figure '7, incorporating a magnet for operating the armature of the switch; and

Figure 9 is a vertical sectional View of a switch similar to Figure 4 incorporating a magnetising winding for the holding electrode.

Referring to the drawings the switch consists of a sealed elongated tubular glass vessel l through the Wall of which pass two electrodes 2 and 3. The electrode 2 passes axially downwards into the vessel l from the top and the electrode 3 passes axially upwards into the vessel at the bottom. Each of these electrodes is sealed into the wall of the vessel by fusing the material of the wall around the electrode in the well known manner. The vessel also contains a ql'- mtity of mercury 4, in which the inner. end of the electrode 3 is permanently immersed, and a plunger. The plunger is in the form of a tubular vessel 5 which. normally oats in the mercury 4. It is provided at its upper end with a magnetic armature 6 in the form of a tube of iron which grips the outside of the plunger 5 tightly. A hole 'l passes through the wall of the plunger at a point between its ends. A' solenoid 8 surrounds the vessel I at an appropriate point. In the normal condition of the switch in which the solenoid 8 is unenergiszd, the plunger 5 iloats in the mercury 4 at such a height that the opening 'l is above the level of the mercury. The lower end of the electrode 2 passes down into mercury` contained in the lower part of the plunger 5. In this condition of the switch there is no electrical connection between the elec- -as that shown in dotted lines.

trodes 2 and 3 because the bodies of mercury into which the electrode 2 dips and in which the electrode 3 is immersed are separated by the wall of the plunger 5. When the solenoid 8 is energised it acts on the armature 6 and draws it, and therefore the plunger 5, down into the position illustrated. Mercury now ows from outside the plunger through the opening 'l into the mercury inside the plunger and as the electrode 2 is still dipping into the last-mentioned body of mercury electrical connectionis now established between the electrodes 2 and 3.

Referring now more particularly to Figure 1, the solenoid 8 of the switch illustrated in this gure is energised from a source of alternating current 9 under the control of the switch III. Ordinarily the armature of a switch, the operating solenoid of which is energised in this way, is liable to cuase a buzzing noise while it is acted on by the solenoid and this may be objectionable. In the switch illustrated the plunger 5 is provided with an auxiliary armature II secured to its lower end and the electrode 3 is made of magnetisable material. It may be made of a nickel iron alloy which is obtainable commercially and which is suitable for fusing in glass and which does not lose its magnetic properties under the action of the heating to which it is subjectedduring fusion. This electrode 3 is mangetised by a permanent magnet I2 which is arranged adjacent toit on the outside of the vessel I in a position such as that illustrated. 'I'he arrangement is' such that when the plunger 5 is pulled down into the position shown' by the energised solenoid 8 the armature II comes close to or into contact with the end of the magnetised electrode 3. The arrangement is such that the magnetised electrode 3 is not strong enough to hold the armature in its displaced position if the solenoid 8 should be de-energised again but is vmade strong enough to reduce the oscillatory movement of the armature and thus the buzzing noise which it causes. Thus, when the solenoid 8 is de-energised the plunger 5 is able to rise, in spite of the magnetised electrode 3, due to its buoyancy with'the result that the bodies of mercury in contact with the two electrodes 2 and 3 are separated at the opening 1 and the switch is opened again.

Figure 2 illustrates a case in which the plunger 5 is to be retained in Aits Vdown position by the magnetised electrode 3, this position being the closed position of the switch. In this case therefore when the solenoid 8 is energised by the source of direct current 9 on closing the switch I0, the plunger is brought down into the position illustrated and the switch is closed. However, if the switch I0 is now opened to de-energise the solenoid 8 the plunger 5 is unable to rise because it is retained in the closed position as a result of the action of the magnetised electrode 3 on the auxiliary armature II. In this case it is, of course, necessary for it to be possible to release the plunger 5 to allow it to return to its normal or iloating condition so as to open the switch again when desired. In the example illustrated in Figure 2 this is provided for by mounting the magnet I2 so that it can be moved into a position in which it no longer exercises a suiciently strong magnetising action on the electrode 3. The way of doing this, which is illustrated diagrammatically in the drawings, is to mount the magnet I2 on the end of a lever I3 which can be swung to move the magnet I 2 into a position such 'When this is done the plunger 5 is, of course, released by the elecaimerai trode 3 so that it can then rise and open the switch in the manner already explained.

Figure 3 shows an arrangement similar in all respects to that of Figure 2 except that here the magnet I2 is arranged in a different position and is moved electro-magnetically to open the switch. The manget is connected to the plunger I 4 of a solenoid I5. When this solenoid I5 is energised it draws the plunger, and therefore the magnet I2, to the right into a position such as that shown in dotted linesvin which the electrode 3 is de-magnetised to release the plunger 5.

In the arrangement of Figure 4 the electrode 3 is provided, not only with a magnetising magnet I2, but with a winding I6 which is in series with the switch so that the current passing through the switch passes through this winding. The direction of winding is such that the winding I 6 exerts a de-magnetising elect on the electrode 3 but the arrangement is such that when the normal current is owing through the switch this action of the winding is insuiflcient to release the plunger 5. If, however, an overload current ows the electrode 3 is de-magnemsed suiiiciently by the winding I6 to release the plunger 5 so that the switch is open. If desired the manget I2 may be made movable so that the plunger can be released by hand also although this is not always necessary. In Figure 4 it is i1- lustrated as being movable in accordance with the arrangement of Figure 2, although it could be made movable in the way shown in Figure 3.

In another arrangement similar to Figure 4, shown specifically in Figure 9, the winding I6' does not act as an overload release device but instead of acting as a winding for de-magnetising the electrode 3 it forms the means for magnetising this electrode. In this case the electrode 3 is normally unmagnetised but is magnetised when the switch is closed, by energising the solenoid 8, by the passage of the current passing through the switch through the winding I6'. If this current should fall, therefore, the electrode 3 becomes de-magnetised and the switch automatically opens. Here again other means such as a movable magnet I2 may be provided for opening the switch by hand or otherwise, as desired.

Figure 5 illustrates an arrangement in which a a de-magnetising winding I6 can be energised by a switch to cause the plunger 5 to be released. The switch is provided with a second contact by means of which it can also be employed to ener--` giSe the solenoid 8. The switch arm is illustrated at I'I and the switch is provided with two contacts I8 and I9. If this switch arm I'I is moved through the path indicated in dotted lines, it will be seen that it causes the following sequence of operations: energising of the solenoid 8 and consequent drawing down of the plunger 5 until it is held down by the electrode 3 which is magnetised by magnet I2; de-energising of solenoid 8, energising of winding I6 to de-magnetise electrode 3 and allow the plunger 5 to rise to open the switch; de-energising of winding I6. Aspring such as 20 may be provided to act on the arm I'I and cause it to move rapidly over the contacts ll and I9.

Figure 6 illustrates an arrangement which is similar to that of Figure 5 except that here the solenoid 8 and the de-.magnetising winding I6 are energised in turn by rectied alternating current derived from a source of alternating current 9 through appropriately arranged rectiers. When the switch arm I1 passes over contact I9, the

rectier 2l is brought into circuit and the rectifier 22 passes the impulses passed by rectifier 2l to solenoid 8. The corresponding rectier 23 arranged in the circuit of Winding I8 will not pass these impulses so that winding I6 is not energised at that time. It is only energised when switch arm I1 passes over contact I8 which brings into circuit rectifier 24, the direction ofwhich corresponds to that of rectifier 23.

In the arrangement of Figure 7 a high resistance coil 26 which is connected across the electrodes 2 and 3 is arranged near t-o a bi-metallic strip 25, the lower end of which is xed. By means of a switch 30 this coil 26 may be connected to a source of current as a result of which the strip 25 is heated and caused to bend to the right. It eventually bridges the contacts III in the circuit of the solenoid 8 of the switch so that this solenoid becomes energised so that the switch is closed in the manner already described. The plunger 5 is then held down by the electrode 3 and the auxiliary armature II, the electrode 3 being magnetised by a magnet I2 as before. When the switch is closed, the heating coil 26 is short-circuited by the switch itself so that the bi-metallic strip 25 then cools and mo-ves back to break the circuit of the solenoid 8. The switch is, however, still held closed by the magnetised Aelectrode 3. A winding I6 surrounds the electrode 3, the winding being connected in series with the switch. According to the direction of the winding I6 it forms an overload deenergising Winding or a. winding magnetising the electrode 3, in which latter case the magnet I2 may be omitted.

Figure 8 illustrates an arrangement which is identical with that of Figure '7 except that here the switch is operated, not by a solenoid 8, but by a movable magnet 8. 'Ihis magnet is of horseshoe shape in plan and is mounted at the upper end of the bi-metallic strip 25. When this strip is moved and the magnet is in the position illustrated, it does not act on the armature 6 but when the bi-metallic strip is heated and moves to the right it moves the magnet until its two limbs embrace the vessel I at a point belowthe normal position of armature Ii which is thus acted upon by the magnet enclosing the switch in the manner already described.v The operation is otherwise similar to that of Figure 7.

I claim:

l. An electric switch comprising a vessel, at least one movable part enclosed in said vessel, electrodes passing into said vessel and sealed in its wall, at least one of said electrodes being of magnetic material, means for acting magnetically on said part to move it to operate the switch, means for magnetising said last-mentioned electrode, said electrode being so disposed that said part moves to within range of the magnetised electrode so as to be retained by its magnetic attraction to hold said switch in one condition, and means for de-magnetising said electrode so as to release said part.

2. An electric switch comprising a vessel, at least one movable part enclosed in said vessel, electrodes passing into said vessel and sealed in its wall, at least one of said electrodes being of magnetic material, means for acting magnetically on said part to move it to operate the switch, means for magnetising said last-mentioned electrode, said electrode being so disposed that said part moves to within range of the magnetised electrode so as to be retained by its magnetic attraction to hold said switch in one condition,

a @winding adjacent to said electrode and means for supplying current to said winding to cause it to neutralise said magnetising means to de-magnetise said electrode to release said part.

3. An electric switch comprising a vessel, at least one movable part enclosed in said vessel, electrodes passing into said vessel and sealed in its wall, at least one of said electrodes being of magnetic material, magnetic means for causing said part to move to operate the switch, means outside said vessel for magnetising said lastmentioned electrode, said electrode being so disposed that -said part moves to within range of the magnetised electrode so as to be retained by its magnetic attraction to hold said switch in one condition, and said magnetising means being movable relatively to said electrode to demagnetise it and release said part.

4. An electric switch comprising a vessel, at least one movable part enclosed in said vessel, electrodes passing into said vessel and sealed in its wall, at least one of said electrodes being of magnetic material, means for acting magnetically on said part to move it tooperate the switch, av winding magnetising said last-mentioned electrode and traversed by a current controlled by said switch, said electrode being so disposed that said part moves to within range of the magnetised electrode so as to be retained by its magnetic attraction to hold said switch in o-ne condition.

5. An electric switch comprising a vessel, at least one movable part enclosed in said vessel, electrodes passing into said Vessel and sealed in its Wall, at least one of said electrodes being of magnetic material, magnetic means for causing said part to move to operate the switch, a winding magnetising said last-mentioned electrode and traversed by a current controlled by said switch, said electrode being so disposed that said part comes within range of the magnetised electrode when moved to an on position in which it is held by said magnetised electrode.

6. An electric switch comprising a vessel, at least one movable part enclosed in said vessel, electrodes passing into said vessel and sealed in its wall, at least one of said electrodes being of magnetic material, mea-ns for acting magnetically on said part to move it to operate the switch, means for magnetising said last-mentioned electrode, said electrode being so disposed that said part moves to within range of the magnetised electrode so as to be retained by its magnetic attraction to hold said switch in one condition, and a winding'traversed by current controlled by said .switch and neutralising the magnetising action of said means so as to de-magnetise said electrode if said current rises sufficiently.

7. An electric switch comprising a vessel, at least one movable part enclosed in said vessel, electrodes passing into said vessel and sealed in its wall, at least one of said electrodes being of magnetic material, a winding acting magnetically on said part to move it to operate the switch, means outside said vessel for magnetising said last-mentioned electrode, said electrode being so disposed that said part comes within its range duringit's movement so as to be retained by its magnetic attraction to hold said switch in one condition, and means for de-magnetising said electrode so as to release said part.

8. Anelectric switch comprising a vessel, at least one movable part enclosed in said vessel, electrodes passing into said vessel and sealed in its wall, at least one of said electrodes being of magnetic material, a Winding acting magnetically on said part to cause it to move to operate said switch, a second winding for magnetising said last-mentioned electrode, said electrode being so disposed that said part when moved by said rst winding moves withinI range of the magnetised electrode so as to be retained by its magnetic attraction to hold sai'd switch in one condition.

`9.An electric switch comprising a vessel, at least one movable part enclosed in said vessel, electrodes passing into said vessel and sealed in its wall, at least one of said electrodes being of magnetic material, a magnet for acting magnetically on said part to move it to operate the switch, means for magnetising said last-mentioned electrode, said electrode being so disposed that said part moves to within range of the magnetised electrode so as to be retained by its magnetic attraction to hold said switch in one condition, thermal means connected to said magnet, a winding heating said thermal means to bring said magnet into the eld. of operation of said part to move said part, means whereby said winding is rendered ineiective when said part has been moved by said magnetic means, and means for demagnetising said electrode.

10. An electric switch according to claim 9, wherein said last-mentioned means comprises a winding traversed by a 'current controlled by the material, means acting on said main armature to cause said part to move to operate the switch, means outside said vessel for magnetising said last-mentioned electrode, said electrode being so disposed. that said auxiliary magnetic armature moves to within range of the magnetised electrode so as to be magnetically attracted by it.

12. An electric switch comprising a. vessel, at least one movable part enclosed in said vessel, electrodes .passing into said vessel and sealed in its wall, at least one of said electrodes being of magnetisable magnetic material, means for acting magnetically on said part to move it to operate the switch, said magnetisable .electrode being so disposed that said part moves to within its range so as to be retained by its magnetic attraction to hold the switch in one conditon, and means for de-magnetising said electrode so as to release said part.

13. An electric switch comprising a vessel of 2o fusible insulating material, atleast one movable part enclosed in said vessel, electrodes passing into said vessel and sealed in its wall by fusion, at least one of said electrodes being of magnetic material, means outside said vessel for magnetising said last-mentioned electrode, means for acting magnetically on said part from outside said vessel to move it to operate the switch, said magnetised electrode being so disposed that said part moves to within its range so as to be retained by its magnetic attraction to hold the switch in one condition, and means for de-magnetising said electrode so as to release said part.

ALFREDO CIANCHI. 

